Over the past two years I have seen a clear new pattern in my gallbladder clinic at Nuffield Health Warwickshire: patients doing extremely well on semaglutide (Ozempic, Wegovy) or tirzepatide (Mounjaro), losing two, three, four stone — and then developing right-sided abdominal pain that turns out to be gallstones. They are usually surprised. They shouldn't have been warned off the drugs, but they should have been warned about this.
Yes, the link is real
This is not internet scaremongering. Gallbladder problems — gallstones and gallbladder inflammation — were reported more frequently in patients taking GLP-1 receptor agonists than placebo across the major clinical trials, and a large pooled analysis of randomised trials confirmed the association, with the risk highest at higher doses, with longer treatment, and when the drugs are used for weight loss specifically. Acute gallbladder disease is listed in the prescribing information for these medicines.
Why it happens: two mechanisms
1. Rapid weight loss itself
This is the dominant factor, and it applies to any rapid weight loss — surgical, dietary or pharmacological. When you lose weight quickly, the liver mobilises cholesterol and secretes more of it into bile. Bile supersaturated with cholesterol crystallises, and crystals grow into stones. Weight loss faster than around 1.5 kg per week meaningfully raises the risk; on effective GLP-1 dosing, many patients lose at that rate for months.
2. A sluggish gallbladder
GLP-1 drugs also reduce gallbladder motility — the organ empties less often and less completely, partly because slower digestion blunts the normal hormonal signal (cholecystokinin) that triggers it to squeeze. Bile that sits still is bile that forms stones. The combination — more cholesterol in the bile, less movement to flush it through — is close to a recipe for stone formation.
Perspective matters
Most people on GLP-1 medication will never develop symptomatic gallstones, and for many patients the metabolic benefits of the weight loss far outweigh this risk. The point is not to avoid the drugs — it is to recognise the symptoms early, because gallstone disease caught at the biliary colic stage is a planned keyhole day-case operation, while gallstone disease ignored can become acute cholecystitis, jaundice or pancreatitis.
The symptoms to watch for
- Biliary colic: intense, gripping pain under the right ribs or across the upper abdomen, typically 30 minutes to a few hours after eating (classically fattier meals), often radiating to the right shoulder blade, lasting one to several hours
- Nausea or vomiting with the pain
- Red flags: fever, pain lasting more than six hours, yellowing of the eyes or skin, dark urine and pale stools — these suggest complications and need same-day assessment
Note the overlap with the ordinary GI side effects of GLP-1 drugs — nausea, bloating, indigestion — which is exactly why gallstones in this group get missed. The distinguishing feature is the pattern: discrete attacks of severe upper-right pain after meals, rather than background queasiness. I cover this distinction in detail in gallstone pain vs indigestion vs IBS.
What to do if this is you
Don't stop the medication on your own initiative, and don't ignore the pain. An ultrasound scan — quick, painless, available within days privately — settles the question. If stones are confirmed and causing symptoms, keyhole gallbladder removal is a definitive, well-tolerated day-case operation, and it can be planned around your medication and your life. There are specific considerations for surgery while on GLP-1 drugs, which I explain in gallbladder surgery while taking Ozempic or Mounjaro.
Frequently asked questions
Does Ozempic cause gallstones?
GLP-1 medicines such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) are associated with an increased risk of gallstones and gallbladder inflammation, driven mainly by rapid weight loss and reduced gallbladder emptying. Most users never develop symptoms, but the risk is real and listed in the prescribing information.
Should I stop Wegovy or Mounjaro if I get gallstones?
Not on your own initiative. Symptomatic gallstones are usually treated by removing the gallbladder, not by stopping the medication — many patients continue GLP-1 therapy after recovery. Discuss any change with your prescriber and surgeon together.
What does gallstone pain feel like on weight-loss injections?
Discrete attacks of severe, gripping pain under the right ribs or upper abdomen, often after meals, lasting one to several hours and sometimes radiating to the right shoulder blade — distinct from the background nausea and bloating the drugs commonly cause.
How quickly can gallstones form on GLP-1 drugs?
Stones can form within months of starting rapid weight loss. Risk is highest with faster weight loss, higher doses and longer treatment duration. Symptoms most often appear during the active weight-loss phase.
Can gallstones from weight loss go away on their own?
Established gallstones rarely dissolve spontaneously. Stones that cause no symptoms can usually be left alone, but stones causing attacks of pain generally warrant keyhole gallbladder removal to prevent complications such as cholecystitis and pancreatitis.